Yesterday, 06:44 PM
CAT D6H Dozer Overview
The Caterpillar D6H is a mid-size crawler dozer introduced in the 1980s, designed for grading, pushing, and land clearing. Powered by a CAT 3306 turbocharged diesel engine producing approximately 165 horsepower, the D6H features a powershift transmission, elevated sprocket design, and modular track frames. With an operating weight of around 40,000 pounds, it became a staple in construction, forestry, and mining operations.
Caterpillar Inc., founded in 1925, has long led the dozer market. The D6H was part of the elevated sprocket revolution, improving undercarriage serviceability and load distribution. Tens of thousands of units were sold globally, and many remain in service today due to their rebuildable structure and parts availability.
Track Frame Failure and Common Symptoms
Cracks in the track frame of the D6H are a known issue, particularly in machines with high hours or those used in rocky terrain. These cracks often appear near the pivot shaft housing or under the final drive, where stress concentrations are highest. Symptoms include:
Terminology Notes
Caterpillar has published a formal repair guideline under document REHS0540, outlining the steps to restore structural integrity. The process includes:
In Iowa, a contractor faced a cracked track frame on his D6H. The local dealer quoted over $20,000 for a new frame, excluding freight and installation. Instead, he sourced a used frame for $800 and spent another $2,000 on plating and welding. The repair held for over 5,000 hours without recurrence.
Another operator in New Zealand discovered a crack after cleaning his machine. He followed the factory procedure and reinforced both sides. He noted that the previous repair had failed due to shallow welds and no internal plating.
Preventive Measures and Upgrade Advice
Cracked track frames on the CAT D6H are a common but manageable issue. With proper gouging, welding, and reinforcement, the frame can be restored to full strength. The elevated sprocket design and modular frame make repairs feasible in the field. Whether using OEM procedures or skilled fabrication, addressing the root cause and reinforcing stress points ensures long-term reliability and safety.
The Caterpillar D6H is a mid-size crawler dozer introduced in the 1980s, designed for grading, pushing, and land clearing. Powered by a CAT 3306 turbocharged diesel engine producing approximately 165 horsepower, the D6H features a powershift transmission, elevated sprocket design, and modular track frames. With an operating weight of around 40,000 pounds, it became a staple in construction, forestry, and mining operations.
Caterpillar Inc., founded in 1925, has long led the dozer market. The D6H was part of the elevated sprocket revolution, improving undercarriage serviceability and load distribution. Tens of thousands of units were sold globally, and many remain in service today due to their rebuildable structure and parts availability.
Track Frame Failure and Common Symptoms
Cracks in the track frame of the D6H are a known issue, particularly in machines with high hours or those used in rocky terrain. These cracks often appear near the pivot shaft housing or under the final drive, where stress concentrations are highest. Symptoms include:
- Visible fractures in the steel frame
- Misalignment of track components
- Oil leaks from pivot shaft seals
- Uneven wear on rollers and idlers
Terminology Notes
- Track Frame: The structural assembly that supports the undercarriage, including rollers, idlers, and final drives.
- Pivot Shaft: A central shaft that allows the track frame to articulate and absorb terrain movement.
- 7018 Electrode: A low-hydrogen welding rod used for structural steel repairs.
Caterpillar has published a formal repair guideline under document REHS0540, outlining the steps to restore structural integrity. The process includes:
- Removing the Track Frame: Allows full access to the crack and surrounding structure.
- Gouging Out the Crack: Use air arc or grinding to remove all damaged metal, ensuring full penetration.
- Welding with 7018 Rods: Apply multiple passes with proper preheat and post-weld cooling.
- Plating Reinforcement: Weld 1-inch steel plates on both the inside and outside of the frame, shaped like a flattened triangle to distribute stress.
- Rounding All Edges: Prevents stress risers and future cracking.
- Inspecting Pivot Shaft Seals and Bushings: Replace worn components during disassembly.
In Iowa, a contractor faced a cracked track frame on his D6H. The local dealer quoted over $20,000 for a new frame, excluding freight and installation. Instead, he sourced a used frame for $800 and spent another $2,000 on plating and welding. The repair held for over 5,000 hours without recurrence.
Another operator in New Zealand discovered a crack after cleaning his machine. He followed the factory procedure and reinforced both sides. He noted that the previous repair had failed due to shallow welds and no internal plating.
Preventive Measures and Upgrade Advice
- Inspect Frame Every 1,000 Hours: Look for early signs of cracking or distortion.
- Upgrade Both Sides Simultaneously: Prevent future failure on the opposite side.
- Use Certified Welders or Boilermakers: Structural repairs require skill and precision.
- Document All Modifications: Helps future technicians and supports resale value.
Cracked track frames on the CAT D6H are a common but manageable issue. With proper gouging, welding, and reinforcement, the frame can be restored to full strength. The elevated sprocket design and modular frame make repairs feasible in the field. Whether using OEM procedures or skilled fabrication, addressing the root cause and reinforcing stress points ensures long-term reliability and safety.
